Safety device

ABSTRACT

An inflation device for a buoyancy body such as a life jacket or life raft having a pressurized gas cylinder mounted within the buoyancy body and including an actuator, preferably in the form of a rotatable shaft, which projects from the interior to the exterior of the body so that it can be used to cause release of gas into the body and is operable from the exterior of the inflation device.

BACKGROUND OF THE INVENTION

The present invention relates to inflation devices for inflation ofbuoyancy bodies such as lifejackets or liferafts.

A well known type of life-jacket comprises an impermeable outer skindefining an internal cavity. Typically, a proportion of this internalcavity is filled with a buoyant material to provide an initial, low,level of buoyancy and the skin is inflated by injection of gas toprovide a higher level of buoyancy when needed. Alternatively, in somelifejackets the internal cavity is initially empty, and must be inflatedto provide any buoyancy.

It is known to provide lifejackets with an externally mounted cylindercontaining pressurised gas for inflation of the outer skin. The cylinderis connected via a one way valve (typically a Schraeder valve) to apassage in flow connection with the internal cavity.

The neck of the externally mounted cylinder is initially sealed by ametal closure diaphragm, and a mechanism is provided whereby thediaphragm is punctured when, for example, an actuating tag is pulled,causing inflation of the lifejacket.

Such lifejackets suffer from a number of disadvantages. The externalcylinder is inconvenient to the wearer as it tends to catch on obstacles(which is a particular drawback on boats, which provide a large numberof obstacles such as ropes, ladders etc). It is also vulnerable tophysical damage by impacts, and is unprotected from the corrosiveeffects of water. Known cylinders typically have a cadmium outer platingwhich, in combination with the metal components of the valve and theactuating mechanism and in the presence of salt water, gives rise toelectrolytic corrosion.

Another problem associated with these known lifejackets arises at lowtemperatures. The cylinders are filled with CO₂ gas which, as itexpands, can freeze, thereby blocking the (usually restricted) passagethrough which the gas enters the internal cavity.

There have been attempts in the past to overcome these problems bymounting the gas cylinder within the internal cavity of the lifejacket.In one such lifejacket an inflation assembly comprising the cylinder andthe mechanism for puncturing its metal closure diaphragm is placed loosewithin the internal cavity, being accessible only via a sealable hole inthe outer skin.

To pierce the closure diaphragm, the user locates the inflation assemblyby feel through the outer skin, and then squeezes a handle through theskin to cause inflation.

This operation requires time and a degree of manual dexterity, which canbe problematic since in emergencies it is often very important toinflate a lifejacket quickly.

Further, exposure to cold, particularly cold water, can make any kind ofmanipulation very difficult the user's hands may become too numb to beused effectively, so that inflation of the lifejacket is hard toachieve.

A further type of lifejacket with an internally mounted inflationcylinder is described in GB 2171962. In this case, the outer skin isformed with a projecting elongate pocket. A movable lever of theinflation assembly projects into the said pocket, and a cord is tied tothe distal end of the outside of the pocket surrounding both the pocketand the lever so that pulling on the cord moves the lever, puncturingthe metal closure diaphragm and inflating the lifejacket.

This lifejacket is complicated to manufacture, since the outer skin mustbe formed to provide the projecting pocket. It is also complicated toassemble; the inflation assembly must first be inserted through a gap ina seam of the outer skin. Then the movable lever must be located in thepocket, and the cord tied around the pocket, retaining the lever, andthe gap in the seam must then be welded closed.

The lifejacket in question is not reusable. The inflation assembly ispermanently sealed within the jacket, so that after one inflation (whichexhausts the gas cylinder) the cylinder cannot be replaced.

Additional problems arise where the inflation device in question isadapted to be automatically triggered when its associated buoyancy bodyis placed in water. Such automatic inflation devices are used onlifejackets and liferafts, and several types are known.

Some known automatic inflation devices are electrically controlled,being responsive either to the reduction in resistance between twoexternal electrical contacts when both are immersed in water, or to theelectromotive force generated by a sea water actuated electric cell. Inthe latter type of device salt water acts as the electrolyte of thecell.

When used to cause inflation of buoyancy bodies, electrical releasedevices suffer from serious disadvantages. Devices which rely on areduction in resistance must include a battery or cell, which is certainto discharge over time and so require periodic maintenance. Largenumbers of life vests are stored in ships and aeroplanes, and must bekept in constant readiness, so that it is important to maximize theservice interval of the release device.

Further, electrical release devices must cause inflation of a buoyancybody by electrical or electromechanical means, and known ways ofachieving this are not ideal. One type of device uses a retainer whichis electrically melted to release an inflation mechanism, but low watertemperatures can prevent melting of the retainer and so cause the unitto fail with potentially life threatening consequences. Another type ofdevice uses an electronically ignited explosive charge to release gas,but there are concerns regarding the safety of detonating such a chargeon a personal flotation device.

Still another important disadvantage of electrically actuated releasedevices in the present context is that they can be accidentallyreleased, e.g., by humidity or spray.

It is also known to provide a mechanical release device to causeautomatic inflation of a buoyancy body. One such device is described inGB 2051212 and comprises first and second internal chambers (the firstchamber being open to ingress of water, while the second chamber issealed) separated from each other by a spring biased diaphragm which ismovable by hydrostatic water pressure within the first chamber. Motionof the diaphragm directly actuates a spring loaded gas release device.

One of the problems associated with such known mechanical releasedevices actuated by hydrostatic pressure arises from the fact that thedepth to which a buoyancy body is immersed is typically small. The smallresultant hydrostatic pressure frequently does not produce a largeenough force to overcome friction in the release device. The problem iscompounded in mechanical devices of the above described type by the factthat the diaphragm must be moved against the force caused by air withinthe second (sealed) internal chamber. Since the air within the secondchamber cannot escape, it effectively biases the diaphragm againstmotion in the release direction.

For these reasons, reliable inflation is often not achieved using knowndevices responsive to and actuated by hydrostatic pressure. Again, thiscan cause non-inflation of a life vest or liferaft which can endangerlife.

Another type of automatic release device suited to use in conjunctionwith inflatable buoyancy bodies comprises a retainer which is softenedor dissolved upon contact with water. For example, a salt plug may beused to retain a spring loaded gas release mechanism, so that when thesalt plug is exposed to water and dissolved, the gas release mechanismis released.

The major problem with this known type of release mechanism is that theretainer tends to absorb moisture from the air, and over time this leadsto unintentional softening of the retainer, with consequent release ofgas and inflation of the buoyancy body. For this reason, the retainer inbuoyancy bodies with this type of release must be periodically replaced.

SUMMARY OF THE INVENTION

It is an object of the present invention to overcome the above describedproblems associated with the prior art.

More specifically, a first object of the present invention is to providean inflation device for a buoyancy body which does not make the buoyancybody inconvenient to wear/use.

It is a further object of the present invention to provide an inflationdevice which can be reliably, automatically actuated upon placement inwater but which is protected from accidental actuation by moisture,spray and humidity.

It is still a further object of the present invention to provide aninflation device which can be reliably actuated at the small hydrostaticpressures associated with shallow immersion in water.

In accordance with a first aspect of the present invention, there isprovided an inflation device for a buoyancy body having an outer skindefining an internal cavity and an aperture in the skin, the inflationdevice comprising cover means adapted to be mounted on the buoyancybody, forming a seal therewith which surrounds the aperture in the skin,means for mounting a gas container within the internal cavity andactuating means extending through the cover means for causing release ofgas from the container, the inflation device being adapted to beautomatically actuated upon immersion and additionally comprising meansdefining a chamber, means defining a first opening or passage forconnecting the chamber to the interior of the buoyancy body, meansdefining a second opening or passage for connecting the chamber to theexterior, a one way valve which normally closes the second opening orpassage, biasing means which constantly urge the actuating means towarda gas release position, and restraint means, comprising a waterdegradable element disposed within the chamber, which normally retainthe actuating means in an inactive position, the one way valve beingadapted to be opened by excess external pressure produced uponimmersion, allowing admission of water to the chamber and consequentrelease of gas from the gas container into the buoyancy body.

Preferably, the cover means is adapted to be removably mounted on thebuoyancy body.

Still more preferably, the cover means defines a recess adapted toreceive a sealing ring of the buoyancy body and thereby to form theseal.

To form an improved seal, in a particularly preferred embodiment thesealing ring comprises a resilient undercut lip for resiliently sealingagainst the recess.

In accordance with a second aspect of the present invention, there isprovided an inflatable buoyancy body comprising an outer skin definingan internal cavity, the buoyancy body being provided with an inflatorcomprising means for mounting a pressurized gas container within thecavity and actuating means extending from the interior to the exteriorof the cavity for causing release of gas from the container, theinflator being adapted to automatically cause inflation of the buoyancybody upon immersion and further comprising a housing defining a chamber,means defining a first opening or passage connecting the chamber to theinternal cavity of the buoyancy body, means defining a second opening orpassage for connecting the chamber to the exterior, a one way valvewhich normally closes the second opening or passage, biasing means whichconstantly urge the actuating means toward a gas release position, andrestraint means, comprising a water degradable element disposed withinthe chamber, which normally retain the actuating means in an inactiveposition, the valve being adapted to be opened by excess externalpressure produced upon immersion allowing admission of water to thechamber and consequent release of gas from the pressurised gas containerinto the buoyancy body.

BRIEF DESCRIPTION OF THE DRAWINGS

Specific embodiments of the present invention will now be described, byway of example only, with reference to the accompanying drawings, inwhich:

FIG. 1 is a cross-sectional view of a manually actuated inflationdevice;

FIG. 2 is a front view of an outer sealing cover according to the deviceshown in FIG. 1;

FIG. 3 is a side view of a closure body forming part of the device shownin FIG. 1;

FIG. 4 shows a shaft and lever of the FIG. 1 device;

FIG. 5 is an exploded view of an automatic inflation device constructedin accordance with the present invention;

FIG. 6 is a cross-sectional view of the FIG. 5 embodiment;

FIG. 7 is a sectional view of the FIG. 5 embodiment seen from the front;

FIG. 8 is a cross-sectional view or a variant of the FIG. 5 embodimentadapted only for manual actuation; and

FIG. 9 is an enlarged cross-section of a resilient sealing ring andassociated components in accordance with the present invention.

DETAILED DESCRIPTION OF THE INVENTION

The illustrated inflation devices are all adapted to be sealinglymounted at an aperture in a buoyancy body, and thereby to mount apressurized gas cylinder within the buoyancy body. In each case,actuating means which can be operated (be it manually or automatically)from outside the buoyancy body are provided.

The device illustrated in FIGS. 1 to 4 will be described first. Verybriefly, this embodiment uses a gas cylinder which is normally sealed bya closure diaphragm 28 at its neck. To inflate the buoyancy body, theuser pulls a cord connected to a radially projecting lever 38, whichrotates a hollow shaft 34. An eccentric portion 36 of the shaft 34 thendrives a spur 32 through the diaphragm 28, releasing gas directly intothe buoyancy body.

This device will now be described in more detail.

As shown in FIG. 1, a flexible outer skin 2 of a buoyancy body such as alifejacket or liferaft is penetrated by a circular opening, theperimeter of which is welded to a resilient "0" ring 4. The "0" ring 4is retained in an annular cavity formed between a closure body 6 and anouter sealing cover 8, and is squeezed by inner faces of the saidannular cavity, forming a seal therewith, and thereby sealing thecircular opening in the outer skin 2.

The closure body 6 (best shown in FIG. 3) comprises a disc portion 10from a front face of which projects a concentric annular collar 12.Slots are formed in the annular collar 12, producing sprung tongues 14projecting beyond the collar which bear, at their ends, outwardlydirected undercut lugs 16.

A front view of the sealing cover 8 is shown in FIG. 2. It has acircular perimeter and is penetrated by a plurality of slots 18 equal innumber to the number of sprung tongues 14.

When the closure body 6 and the outer sealing cover 8 are assembledtogether, as in FIG. 1, the annular collar 12 of the closure body islocated in an annular recess 20 in the rear face of the sealing cover,and the sprung tongues 14 project through the slots 18 in the sealingcover so that the undercut lugs 16 engage with the front face of thesealing cover and thereby hold the body and cover together.

Projecting from the rear face of the closure body is a connecting elbowportion 22 with a vertical threaded bore 24 to receive the neck of a gascylinder 26. The gas cylinder is initially sealed by the metal closurediaphragm 28.

Below the vertical threaded bore 24, and in communication therewith, isa vertical stepped bore 30, within which is mounted a slide member fromwhich the spur 32 projects upwards. The tip of the spur lies adjacentthe metal closure diaphragm 28.

The closure body 6 has a horizontal bore within which is journalled thehollow shaft 34 with the eccentric portion 36 which is received in abore in the slide member.

As FIGS. 1 and 4 show, the hollow shaft 34 is provided with a radiallyprojecting lever 38, which is retained between opposing faces of theclosure body 6 and the sealing cover 8. A substantially gas impermeableseal is provided by two "0" rings 40 contained in respective annularcavities between the closure body 6 and the lever 38 and between thesealing cover 8 and the lever 38, so that gas cannot escape around thehollow shaft 34.

At a lower edge of the lever 38 are two indicator discs 41, coloredgreen, while at an upper edge the lever is connected to a cord 42 (seeFIG. 4).

The cord 42 is led out through one of two arcuate slots 44 in thesealing cover 8 (see FIG. 2). At the lower end of both of the arcuateslots 44 are holes 46 through which the two green indicator discs 41 cannormally be seen.

When it is desired to inflate the buoyancy body, the user pullsdownwards on the cord 42, thereby rotating the hollow shaft 34. As theshaft rotates, the eccentric portion 36 forces the slide member upwardsso that the upwardly projecting spur 32 punctures the closure diaphragm28, and the gas within the cylinder is released directly into thebuoyancy body.

A visual indication that the gas has been released is provided by theindicator discs 41, which are no longer visible through the holes 46.

Should the buoyancy body begin to deflate, it can be topped up via anoral inflation tube 48 provided on the front of the sealing cover 8.This tube is in flow communication with the hollow shaft 34, and thuswith the interior of the buoyancy body. It is sealed using a one wayvalve (not shown) connected to its upper open end. The one way valve isfurther connected to a flexible tube or mouthpiece into which the usercan blow.

It will be appreciated that the inflation device described above issecurely located relative to the buoyancy body, in contrast to the twoprior art inflation devices with internal cylinders described above,which are loose within the buoyancy body.

A further advantage is the ease of assembly achieved by this inflationdevice. The gas cylinder 26 and the mounting body 6 are first insertedthrough the hole in the outer skin 2, then the sealing cover 8 is pushedover the circular lip 12 and is instantly locked in place by theundercut lugs 16 in a quick and simple operation.

The inflation device can be quickly and easily removed for maintenanceor for replacement of the cylinder simply by pushing back the undercutlugs 16, removing the sealing cover 8 and drawing the inflation deviceand gas cylinder out through the opening in the outer skin 2.

Problems of physical damage and corrosion are substantially reducedbecause most of the working parts of the present invention are Protectedwithin the sealed environment of the buoyancy body.

A dessicant may be placed within the buoyancy body to provide furtherprotection.

Since gas does not have to enter the buoyancy body through a passage, asin the prior art devices with external cylinders, there is a reducedrisk of frozen gas preventing gas flow.

All of the above described advantages are also achieved by theautomatically actuable inflation device according to the presentinvention illustrated in FIGS. 5, 6 and 7, which will now be described.

Briefly, this embodiment is like the previously described device in thatit uses a normally sealed gas cylinder 100 which is pierceable by a spur102 driven by an eccentric portion of a shaft 104. In this instance,however, the shaft is constantly urged to rotate by a spiral spring 106and is normally prevented from rotating by restraint means 108comprising a water degradable element 110. The water degradable elementis contained in a chamber within the inflation device, this chamberbeing in flow communication with the interior of the buoyancy body butbeing normally sealed to the exterior by a valve 112.

When external pressure on the valve 112 is increased due to submersion,this valve opens, admitting water which destroys the water degradableelement 110. The restraint means 108 is thus rendered inoperative sothat the shaft 104 is rotated by the spiral spring 106, and gas isthereby released.

The present embodiment of the invention will now be described in moredetail.

As in the above described manually actuated inflation device, the gascylinder 100 of the present embodiment is contained within a buoyancybody in use, (the skin of the buoyancy body is shown at 114 in FIG. 6).The neck of the gas cylinder 100 is threadedly received in an inclinedbore in a body 116. The shaft 104, penetrated by a through-going axialbore, is journalled in and extends forward from a bore 120 in the body116 (in what follows, the forward direction is the direction from insidethe buoyancy body to outside the buoyancy body--i.e., from left to rightas shown in FIG. 6, and "front" and "rear" are to be correspondinglyconstrued).

A rearward portion 122 of the shaft 104 is eccentric, and journalledthereon is a ring 124 to which is joined the spur 102, the spurprojecting through a tapered vertical bore 126 in the body 116 toward ametal closure diaphragm 128 of the gas cylinder. As in the previouslydescribed embodiment, rotation of the shaft causes the spur 102 to beforced through the diaphragm 128, releasing gas from the cylinderdirectly into the buoyancy body.

Mounting of the present inflation device on the buoyancy body isachieved by means of a resilient sealing ring 130 joined to orintegrally formed with the skin 114 of the buoyancy body and sealinglyreceived in an annular recess defined between a front face of the body116 and a rear face of a locking ring 132. The body and locking ring areadapted to be attached to one another by means of sprung undercut lugs134 integrally formed with and projecting forward from the body 116,which have outwardly directed teeth 136 for engagement with respectiveshoulders 138 provided at a radially inner face of the locking ring 132(see FIG. 5). In this way, a part turn lock is produced.

Thus, to mount the device on a buoyancy body, one need only place thegas cylinder 100 and body 116 within the buoyancy body, locate thesealing ring 130 on the front face of the body, and push the lockingring 132 (bearing additional components, to be described below) onto thebody, and rotate to lock.

Removal of the device is also very simple. It will be seen in FIG. 5that the shoulders 138 do not extend around the entire circumference ofthe locking ring 132. Rotation of the locking ring relative to the bodythus causes the teeth 136 to disengage from the shoulders 138, allowingseparation of the locking ring from the body.

While the present embodiment is adapted to be automatically activatedupon immersion, it is provided with a "back-up" mechanism for manualactivation. The mode of operation of this mechanism is similar to theoperation of the previously described manual inflation device, althoughthe details of the mechanism are different and will now be described.

An actuator is provided in the form of a single piece moulding offlexible plastics comprising an elongate cord 140 and an actuator ring142. As before, the cord 140 is led out of the device to be accessibleto the user. The actuator ring 142 is received on a reduced diameterportion of a drive ring 144, and rotation of the actuator ring relativeto the drive ring is prevented by means of a projection 146 from theradially inner face of the actuator ring 142, which engages with atongue 148 at the radially outer face of the drive ring 144. The drivering itself engages with the shaft 104.

Now, in the assembled device the cord 140 is passed in a clockwisedirection (when the device is viewed from the front) around the actuatorring 142, so that when the user pulls sufficiently hard on the cord theactuator ring is rotated, and this rotation is transmitted via the drivering 144 to the shaft 104, causing rotation of the shaft and consequentrelease of gas. During rotation of the shaft, a ratchet (to be describedbelow) connecting the shaft to the automatic release mechanism slips.

The shaft 104 comprises, part way along its length, an integrally formedcollar 150 which, by abutment against a front face of the body 116 and arear face of a mounting ring 152 (to be described below) substantiallyprevents longitudinal motion of the shaft. Immediately to the rear ofthe collar 150 is a first sealing ring 154 disposed within an annularcavity defined between the shaft 104, its collar 150 and the body 116. Aportion of the shaft 104 in front of the collar 150 is journalled in abore of the mounting ring 152, and this portion of the shaft comprisesan annular recess containing a second sealing ring 156. The first andsecond sealing rings 154, 156 serve to prevent ingress of water oregress of gas.

The mounting ring 152 comprises a circular disc portion 159 from therear face of which projects a collar 160; the bore which receives theshaft 104 is within the collar 160. Joined to the front face of themounting ring 152 is a substantially cup-shaped housing 162, and betweenthe housing and the mounting ring is defined an internal chamber 164containing components of the automatic activation mechanism. It shouldbe noted that the chamber 164 communicates with the interior of thebuoyancy body via the bore in the shaft 104, and is normally sealed fromthe exterior by the valve 112.

The assembly comprising the mounting ring 152 and the housing 162 isattached at a front face of the locking ring 132 by means of undercutlugs 166, projecting from the rear face of the circular disc portion158, whose outwardly directed teeth engage with corresponding shoulders168 formed at a radially inner face of the locking ring 132.

Within the chamber 164 is contained the coiled spring 106 which, actingvia a ratchet wheel 170, constantly urges the shaft 104 to rotate in aclockwise direction. Both axially outer faces of the ratchet wheel 170are provided with ratchet teeth 172. The ratchet teeth on the rear faceof the ratchet wheel 170 engage with corresponding ratchet teeth 174formed on the front end of the shaft 104, so that the ratchet wheel 170can drive the shaft 104 in a clockwise direction but the shaft remainsfree (particularly during manual operation) to rotate clockwise relativeto the ratchet wheel.

Rotation of the ratchet wheel 170 in a clockwise direction is normallyprevented by engagement of the ratchet teeth at its front face withcorresponding ratchet teeth formed on the rear face of a restraint wheel176. The said restraint wheel 176 comprises a reduced diameter hub 177at its front face which is received in a bore in a front face of thehousing 162. Further, at its radially outer face the restraint wheel 176is provided with two engagement projections 178, which normally engagewith a sprung restraint 180 to prevent rotation of the restraint wheel.

The sprung restraint 180 comprises two approximately crescent shapedmembers 181 (best seen in FIG. 5) joined at respective first tips by aresilient bridge portion 182. In addition, respective second tips of thecrescent shaped members are normally joined by the water degradableelement 110, which according to the present embodiment is simply a smallpiece of water softenable paper. Adjacent their respective first tips,both crescent shaped members are penetrated by respective bores 184which are located on pegs 186 projecting rearward from the front face ofthe housing 162, the sprung restraint being thereby prevented fromrotating. Rearward motion of the sprung restraint 180 is prevented by apartition washer 188.

In the normal configuration of the device (prior to any submersion) theresilient bridge portion 182 exerts a force directed to urge the secondtips of the crescent shaped members 181 apart, but this force isresisted by the water degradable element 110. Consequently, cutaways 190at respective inner faces of the crescent shaped members 181 arenormally maintained in engagement with the engagement projections 178 ofthe restraint wheel 176, preventing rotation both of this wheel and (viathe ratchet wheel 170) of the shaft 104.

When water enters the cavity 164, however, it contacts and degrades ordissolves the water degradable element 110, allowing the crescent shapedmembers 181 to spring apart. The shaft is thus rendered free to rotateunder the influence of the coiled spring 106, causing release of gas aspreviously described.

Entry of water to the cavity 164 occurs via a tube 192 which isintegrally formed with the housing 162 and which lies adjacent the waterdegradable element 110, so that any water entering will immediatelycontact said element.

However, as has been noted above, the tube 192 is normally closed by thevalve 112. This valve comprises a substantially frusto-conical valvemember 194 urged, outwardly of the cavity 164, toward an annular valveseat 196, by a helical spring 198.

The valve 112 excludes spray and humidity from the chamber 164,preventing the type of unwanted activation by such factors explainedwith reference to the prior art.

To open the valve 112, the biasing exerted on the valve member 194 bythe helical spring 198 must be overcome by a differential between theexterior pressure and the interior pressure within the chamber 164(which, because the chamber communicates with the interior of thebuoyancy body, is equal to the pressure within the buoyancy bodyitself). Just such a pressure differential is created when the inflationdevice is submerged: external water pressure then exceeds internalpressure and so opens the valve 112, admitting water to the chamber andcommencing the gas release process. Once the gas cylinder 100 ispunctured, internal pressure increases very rapidly, closing the valve112 and preventing further ingress of water.

FIG. 9 illustrates, to an enlarged scale, a particularly advantageousform of the sealing ring 132 used in mounting the device on the buoyancybody. The outer surface of the sealing ring is not a complete circle incross section; it is instead cut away at the region where it meets theskin of the buoyancy body to form an undercut lip 200, which pressesoutward resiliently against the annular recess in the body 116, formingan improved seal. The seal is improved still further when gas pressurewithin the buoyancy body increases upon inflation, since this pressureacts on the exposed surface of the undercut lip 200, forcing said lipstill more firmly against the body 116.

A particular advantage of the present embodiment is that, by virtue of aform of modular design, the bulk of the components (excluding thoseconcerned with automatic activation) can be used in a simple,manual-release-only, device. FIG. 8 illustrates this form of the device.Quite simply, the mounting ring 152 has been replaced with a cover 210.All of the components which, in the automatic version, lie forward ofthe mounting ring 152 (i.e., the components concerned with automaticactivation--the valve, spring, restraint mechanism, housing etc.) areomitted. The remaining components function, as previously described, topermit manual activation.

We claim:
 1. An inflation device for a buoyancy body having an outerskin defining an internal cavity and an aperture in the skin, theinflation device comprising cover means adapted to be mounted on thebuoyancy body, forming a seal therewith which surrounds the aperture inthe skin, means for mounting a gas container and actuating means forcausing release of gas from the container, the inflation device beingadapted to be automatically actuated upon immersion and additionallycomprising means defining a chamber, means defining a first opening orpassage for connecting the chamber to the interior of the buoyancy bodywhereby pressure in the chamber is equalized with pressure at theinterior of the buoyancy body, means defining a second opening orpassage for connecting the chamber to the exterior, a one way valvewhich normally closes the second opening or passage, biasing means whichconstantly urge the actuating means toward a gas release position, andrestraint means, comprising a water degradable element disposed withinthe chamber, which normally retain the actuating means in an inactiveposition, the one way valve being adapted to be opened by excessexternal pressure, relative to the pressure within the chamber, producedupon immersion, allowing admission of water to the chamber andconsequent release of gas from the gas container into the buoyancy body.2. An inflation device according to claim 1, wherein the cover means isadapted to be removably mounted on the buoyancy body.
 3. An inflationdevice according to claim 2, wherein the cover means defines a recessadapted to receive a sealing ring of the buoyancy body and thereby toform the seal.
 4. An inflation device according to claim 3, wherein thecover means comprises two mutually attachable parts between which therecess is formed.
 5. An inflation device according to claim 4, whereinone of the two parts of the cover means is provided with undercut lugsfor attachment to the other of the two parts.
 6. An inflation deviceaccording to any of claims 3 to 5, wherein the sealing ring comprises aresilient undercut lip for resiliently sealing against the recess.
 7. Aninflation device according to claim 1, wherein the actuating meanscomprise a rotatably journalled shaft which extends through the covermeans.
 8. An inflation device according to claim 7, wherein the shaftcomprises or is connected to an eccentric associated with a gas releasemember which is adapted to pierce the gas container, so that rotation ofthe shaft causes linear displacement of the gas release member andconsequent release of gas.
 9. An inflation device according to claim 8,further comprising a cord connected via a lever to the shaft, so thattension in the cord causes rotation of the shaft.
 10. An inflationdevice according to claim 1, in which the first opening or passage isformed by a bore in the shaft.
 11. An inflation device according toclaim 1, wherein the biasing means comprise a spiral spring.
 12. Aninflatable buoyancy body comprising an outer skin defining an internalcavity, the buoyancy body being provided with an inflator comprisingmeans for mounting a pressurized gas container and actuating means forcausing release of gas from the container, the inflator being adapted toautomatically cause inflation of the buoyancy body upon immersion andfurther comprising a housing defining a chamber, means defining a firstopening or passage connecting the chamber to the internal cavity of thebuoyancy body, whereby pressure in the chamber is equalized withpressure in the internal cavity of the buoyancy body, means defining asecond opening or passage for connecting the chamber to the exterior, aone way valve which normally closes the second opening or passage,biasing means which constantly urge the actuating means toward a gasrelease position, and restraint means, comprising a water degradableelement disposed within the chamber, which normally retain the actuatingmeans in an inactive position, the valve being adapted to be opened byexcess external pressure, relative to the pressure within the chamber,produced upon immersion allowing admission of water to the chamber andconsequent release of gas from the pressurized gas container into thebuoyancy body.
 13. An inflation device as claimed in claim 1, whereinthe means for mounting the gas container are such as to mount the gascontainer within the buoyancy body and the actuating means extendthrough the cover means.